π-Topology and spin alignment in the photo-excited states of phenylanthracene-t-butylnitroxide radicals
π-Topology and spin alignment in the photo-excited states of phenylanthracene-t-butylnitroxide radicals
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苯基蒽-叔丁基硝基氧自由基光激发态的π拓扑和自旋排列
DOI：
10.1039/c5cp05994a
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
S. Miyamoto and K. Koide
中科院分区：
文献类型：
--
作者：
Y. Teki;S. Miyamoto and K. Koide
本文用时间分辨ESR和瞬态吸收光谱研究了π共轭自旋体系9-蒽-（3-苯基-叔丁基氮氧自由基）自由基（1 m）和9-蒽-（4-苯基-叔丁基氮氧自由基）自由基（1 p）体系的π拓扑结构与光激发高自旋态的关系。对于间位异构体1 m，观察到激发的四重态高自旋态（S = 3/2），而对于对位异构体1 p，仅检测到弱的二重态信号（S = 1/2）。对于1 m的四重态，g值和精细结构参数被确定为g = 2.005，D = 0.0250 cm−1，E = 1.000 cm−1。基于量子化学从头计算的自旋密度分布，讨论了分子内自旋取向的机制和自旋极化在激发态中的作用.
We have studied the relationship between the π-topology and the photo-excited high-spin states of π-conjugated spin systems, 9-anthracen-(3-phenyl-t-butylnitroxide) radical (1m) and 9-anthracen-(4-phenyl-t-butylnitroxide) radical (1p) systems, by time-resolved ESR and transient absorption spectroscopies. For the meta-isomer, 1m, the excited quartet high-spin state (S = 3/2) was observed, while for the para-isomer, 1p, only a weak signal of the doublet state (S = 1/2) was detected. For the quartet state of 1m, the g value and fine-structure parameters have been determined to be g = 2.005, D = 0.0250 cm−1, and E = ∼0.0 cm−1. The mechanism of intramolecular spin alignment and the role of spin polarization in the excited states have been discussed based on the spin density distribution calculated by ab initio molecular orbital calculations.